1. Field of the Invention
The present invention relates to a sputtering apparatus employed for producing a semiconductor device, an optical disk, a magnetic-recording medium, a liquid-crystal display device, a solar battery, and the like.
2. Description of Related Art
Conventionally, in a process of producing a semiconductor device, an optical disk, a magnetic-recording medium, a liquid-crystal display device, a solar battery, and the like, a sputtering apparatus is employed to form a functional thin-film or a protective film which forms part of the above-described products. To form a multi-layer film structure, what is commonly performed is: a sputtering unit is exclusively and independently provided for forming each layer of the film; or a plurality of different targets are provided in a single apparatus in order to change the pressure and other formation factors of each film, and sputtering is executed by plasma discharging at every film formation step in sequence. However, these methods have a lower efficiency in mass production. Consequently, there recently has been proposed an in-line sputtering apparatus comprising a plurality of film-forming chambers each having an exclusive exhaust pump for each target, and the film-forming chambers are connected to each other via gates. This in-line sputtering apparatus has drawn attention due to its superior productivity.
However, a conventional in-line sputtering apparatus has comprised, for every target, an exclusive film-forming chamber equipped with a gate and an exclusive high-vacuum pump such as a cryopump or a turbo-pump so as to allow setting of the sputtering pressure arbitrarily and independently for each different target. Due to this configuration, which has required a number of film-forming chambers, gates, high-vacuum pumps, and the like, the cost of the apparatus is high.
FIG. 4 is a schematic illustration showing a representative configuration of a conventional in-line sputtering apparatus.
In FIG. 4, film-forming vacuum chambers 417, 418, and 419 are provided, in order, between an input chamber 405 and an output chamber 406. The input chamber 405 and the film-forming vacuum chamber 417, and the vacuum chamber 419 and the output chamber 406 are connected by gate valves 407 and 408, respectively. Likewise, the vacuum chambers 417 and 418, and the vacuum chambers 418 and 419 are connected by gate valves 415 and 416, respectively.
A cryopump 409, a sample holder 410, and a deposition shield member 414 are provided in each of the film-forming vacuum chambers 417 to 419. Each sputtering process is performed by a respective one of the different targets 401 to 403 to deposit a film on the corresponding sample in each of the film-forming vacuum chambers 417 to 419 to which Ar gas for performing the sputtering is supplied via each of the MFCs (mass-flow controllers) 1 to 3.
However, there has been a drawback in the conventional in-line sputtering apparatus of the prior art such that the apparatus has required a number of expensive components such as exhaust pumps and gates to complete a single apparatus, which has resulted in making the price of the apparatus expensive. In addition, the above apparatus cannot always form the multi-layer film effectively.